Method and apparatus for supporting a supplementary uplink frequency in wireless communication system

ABSTRACT

The disclosure relates to a communication technique and a system thereof that fuses a 5G communication system for supporting higher data rate after a 4G system. The disclosure is enabled to be applied to intelligent services (for example, smart home, smart building, smart city, smart car or connected car, health care, digital education, retail, security and safety related services, etc.) based on 5G communication technology and IoT related technology. A method for performing a random access by a terminal is provided. The method includes receiving information for performing a random access from a base station (BS), determining a frequency band to perform the random access among a first frequency band and a second frequency band based on the information for performing the random access, and transmitting a first random access preamble to the BS on the determined frequency band.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 16/050,573, filed on Jul. 31, 2018, which will be issued as U.S.Pat. No. 10,973,056 on Apr. 6, 2021 and was based on and claimedpriority under 35 U.S.C § 119(a) of a Korean patent application number10-2017-0099778, filed on Aug. 7, 2017, in the Korean IntellectualProperty Office, the disclosure of which is incorporated by referenceherein in its entirety.

BACKGROUND 1. Field

The disclosure relates to a terminal, a base station, and operationsthereof in a mobile communication system.

2. Description of Related Art

In addition, the disclosure relates to a method for reducing powerconsumption and configuring data transmission delay for eachtransmission unit when a terminal performs a discontinuous reception(DRX) operation in a wireless communication system in which a pluralityof transmission units coexists.

To meet the demand for wireless data traffic having increased sincedeployment of fourth generation (4G) communication systems, efforts havebeen made to develop an improved fifth generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘Beyond 4G Network’ or a ‘Post long term evolution(LTE) System’. The 5G communication system is considered to beimplemented in higher frequency millimeter wave (mmWave) bands, e.g., 60GHz bands, so as to accomplish higher data rates. To decreasepropagation loss of the radio waves and increase the transmissiondistance, the beamforming, massive multiple-input multiple-output(MIMO), full dimensional MIMO (FD-MIMO), array antenna, an analog beamforming, large scale antenna techniques are discussed in 5Gcommunication systems. In addition, in 5G communication systems,development for system network improvement is under way based onadvanced small cells, cloud radio access networks (RANs), ultra-densenetworks, device-to-device (D2D) communication, wireless backhaul,moving network, cooperative communication, coordinated multi-points(CoMP), reception-end interference cancellation and the like. In the 5Gsystem, Hybrid frequency shift keying (FSK) and QAM Modulation (FQAM)and sliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the internetof things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The internet ofeverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a machine-to-machine (M2M)communication, machine type communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing information technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, MTC, and M2M communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RAN as theabove-described Big Data processing technology may also be considered tobe as an example of convergence between the 5G technology and the IoTtechnology.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providea method that can reduce power consumption and configure a datatransmission delay for each transmission unit when a terminal performs adiscontinuous reception (DRX) operation in a wireless communicationsystem in which a plurality of transmission units coexists.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

In accordance with an aspect of the disclosure, a method for performinga random access by a terminal is provided. The method includes receivinginformation for performing a random access from a base station (BS),determining a frequency band to perform the random access among a firstfrequency band and a second frequency band based on the information forperforming the random access, and transmitting a first random accesspreamble to the BS on the determined frequency band.

The information for performing the random access may include at leastone of threshold value information for determining the frequency band orinformation on power for transmitting the first random access preamble.

The frequency band to perform the random access may be determined amongthe first frequency band the second frequency band based on thethreshold value information for determining the frequency band and powerinformation of the terminal.

The method for performing the random access by the terminal may furtherinclude receiving information for changing the frequency band from theBS via downlink control information (DCI), and transmitting a secondpreamble for performing the random access to the BS on the changedfrequency band.

In accordance with another aspect of the disclosure, a method forperforming a random access by a base station (BS) in a wirelesscommunication system is provided. The method includes generatinginformation for performing a random access in a first frequency band ora second frequency band, transmitting the generated information to aterminal, and receiving a random access preamble for performing therandom access from the terminal on a frequency band determined based onthe generated information.

The information for performing the random access may include at leastone of threshold value information for determining the frequency band orinformation on power for transmitting the random access preamble.

The decided frequency band may be determined based on the thresholdvalue information for determining the frequency band and powerinformation of the terminal.

The method for performing the random access by the base station mayfurther include: generating information for changing the determinedfrequency band, and transmitting the information for changing thedetermined frequency band to the terminal via downlink controlinformation (DCI).

In accordance with another aspect of the disclosure, a terminal isprovided. The terminal includes a transceiver, and at least oneprocessor configured to control the transceiver to receive informationfor performing a random access from a base station (BS), determine afrequency band to perform the random access among a first frequency bandand a second frequency band based on the information for performing therandom access, and control the transceiver to transmit a first randomaccess preamble to the BS on the determined frequency band.

The information for performing the random access may include at leastone of threshold value information for determining the frequency band orinformation on power for transmitting the first random access preamble.

The at least one processor may determine the frequency band to performthe random access among the first frequency band and the secondfrequency band based on the threshold value information for determiningthe frequency band and power information of the terminal.

The at least one processor may control the transceiver to receiveinformation for changing the frequency band from the BS via downlinkcontrol information (DCI) and control the transceiver to transmit asecond random access preamble for performing the random access to the BSon the changed frequency band.

In accordance with another aspect of the disclosure, a base station isprovided. The base station includes a transceiver, and at least oneprocessor configured to generate information for performing a randomaccess in a first frequency band or a second frequency band, control thetransceiver to transmit the generated information to the terminal, andcontrol the transceiver to receive, from the terminal, a random accesspreamble for performing the random access on a frequency band determinedbased on the generated information.

The information for performing the random access may include at leastone of threshold value information for determining the frequency band orinformation on power for transmitting the random access preamble.

The at least one processor may generate information for changing thedetermined frequency band and control the transceiver to transmitinformation for changing the determined frequency band to the terminalvia downlink control information (DCI).

According to another embodiment of the disclosure, a terminal canoperate a configuration of a specific timer according to a transmissionunit among DRX operations according to a transmission unit of eachserving cell and adjust and reduce a transmission delay.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A is a diagram illustrating a structure of a next-generationmobile communication system according to an embodiment of thedisclosure;

FIG. 1B is a conceptual diagram for applying a supplementary uplinkfrequency according to an embodiment of the disclosure;

FIG. 1C is a conceptual diagram in which a terminal selects a pluralityof uplink frequencies according to an embodiment of the disclosure;

FIG. 1D is a diagram for describing a process in which a standby modeterminal selects one uplink frequency according to an embodiment of thedisclosure;

FIG. 1E is a flowchart of an operation in which a standby mode terminalselects one uplink frequency according to an embodiment of thedisclosure;

FIG. 1F is a diagram for describing a process in which a connection modeterminal selects one uplink frequency according to an embodiment of thedisclosure;

FIG. 1G is a diagram for describing a process of configuring one uplinkfrequency to a terminal that switches a connection mode to a standbymode according to an embodiment of the disclosure;

FIG. 1H is a block diagram illustrating an internal structure of aterminal according to an embodiment of the disclosure;

FIG. 1I is a block diagram illustrating a configuration of a basestation according to an embodiment of the disclosure;

FIG. 2A is a diagram illustrating a structure of a long term evolution(LTE) system according to an embodiment of the disclosure;

FIG. 2B is a diagram illustrating a radio protocol structure of an LTEsystem according to an embodiment of the disclosure;

FIG. 2C is a diagram illustrating an embodiment in which a timing ofperforming a discontinuous reception (DRX) operation is schematized in asituation where a plurality of transmission units coexists according toan embodiment of the disclosure;

FIG. 2D is a diagram illustrating an embodiment in which a timing ofperforming a DRX operation is schematized in a situation where theplurality of transmission units coexists according to an embodiment ofthe disclosure;

FIG. 2E is a diagram illustrating an operational order of a terminal atthe time of performing a DRX operation in a situation where a pluralityof transmission units coexists according to an embodiment of thedisclosure; and

FIG. 2F is a block diagram of a terminal according to an embodiment ofthe disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

First Embodiment

FIG. 1A is a diagram illustrating a structure of a next-generationmobile communication system according to an embodiment of thedisclosure.

Referring to FIG. 1A, a radio access network of a next-generation mobilecommunication system includes a new radio base station (new radio nodeB, hereinafter, referred to as NR NB) 1 a-10 and a new radio corenetwork (NR CN) 1 a-05. A user terminal (new radio user equipment,hereinafter, referred to as NR UE or terminal) 1 a-15 is connected to anexternal network through the NR NB 1 a-10 and the NR CN 1 a-05.

In FIG. 1A, the NR NB 1 a-10 corresponds to an (evolved node B (eNB) ofthe existing long term evolution (LTE) system. The NR NB may beconnected to the NR UE 1 a-15 via a radio channel and may provide asuperior service to the existing Node B. In the next-generation mobilecommunication system, since all user traffic is served through a sharedchannel, a device is required, which collects and schedules stateinformation such as a buffer statue, an available transmission powerstate, and a channel state of UEs and the NR NB 1 a-10 takes charge ofcollecting and scheduling the state information. One NR NB typicallycontrols multiple cells. In order to implement high-speed datatransmission compared to existing LTE, an existing maximum bandwidth ormore may be provided and additionally, beam-forming technology may bemerged using orthogonal frequency division multiplexing (OFDM) as aradio access technology. Further, an adaptive modulation & coding (AMC)scheme is adopted, which determines a modulation scheme and a channelcoding rate according to the channel state of the terminal. The NR CN 1a-05 performs functions such as mobility support, bearer configuration,and a QoS configuration. The NR CN as a device that is in charge ofvarious control functions as well as a mobility management function forthe terminal is connected to multiple base stations. In addition, thenext-generation mobile communication system may interlock with theexisting LTE system and the NR CN is connected to a mobile managemententity (MME) 1 a-25 through a network interface. The MME is connectedwith an eNB 1 a-30 which is the existing base station.

FIG. 1B is a conceptual diagram for applying a supplementary uplinkfrequency according to an embodiment of the disclosure.

Referring to FIG. 1B, in the mobile communication system, inconsistencyof the service areas in the uplink and downlink may occur. Theinconsistency occurs because channel characteristics of the uplink andthe downlink are different or maximum transmission power of the terminalis limited. Typically, the downlink service area is wider than theuplink service area. For example, in a 3.5 GHz time division duplex(TDD) system, the downlink service area 1 b-05 is wider than the uplinkservice area 1 b-10. In this case, a first terminal 1 b-20 does not havea problem in receiving the service in the uplink and the downlink, butthe second terminal 1 b-25 has a problem in successfully transmittingdata to a base station 1 b-15. Accordingly, in order to eliminate theproblem due to the inconsistency, an effective service area of thedownlink is reduced to coincide with the uplink. That is, although thedownlink may provide a wider service area, the uplink service area isalso limited.

In the next-generation mobile communication system, the terminal mayapply the uplink frequency having a wider service area in order to solvethe performance limitation due to such inconsistency. That is, asupplementary uplink (1 b-30) of 1.8 GHz apart from the uplink (1 b-35)of 3.5 GHz is additionally provided to the terminal. Due to thefrequency characteristics, the lower a frequency band, the longer aradio signal propagation distance. Thus, a frequency of 1.8 GHz, whichis lower than 3.5 GHz, enables the wider service area for the terminal.Therefore, a second terminal 1 b-50 may successfully transmit data tothe base station 1 b-40 using the uplink 1 b-30 of 1.8 GHz. Further,since a first terminal 1 b-45 may use both the 1.8 GHz and 3.5 GHzuplinks irrespective of a service area problem, the first terminal 1b-45 may select and use one of 1.8 GHz and 3.5 GHz for the purpose ofdispersing an uplink access congestion. The supplementary uplinkfrequency may be an LTE frequency.

FIG. 1C is a conceptual diagram in which a terminal selects a pluralityof uplink frequencies according to an embodiment of the disclosure.

Referring to FIG. 1C, as mentioned above, the terminal needs to decidewhich frequency to use among a plurality of uplink frequencies. Forexample, a terminal 1 c-15 selects one of the next generation mobilecommunication frequency 1 c-05 of 3.5 GHz and the supplementary uplinkfrequency 1 c-10 of 1.8 GHz to attempt the random access. Although theterminal may use both uplink frequencies, complexity increases in orderto support the use of both uplink frequencies. Therefore, in thedisclosure, it is assumed that the random access and uplink datatransmission are performed by selecting one of the plurality of uplinkfrequencies provided by the base station. That is, the plurality ofuplink frequencies is not used at the same time. A terminal in a standbymode selects the uplink frequency to attempt the random access usingpredetermined information provided from the base station through systeminformation. In order to limit the complexity, the terminal in aconnection mode may not change the used uplink dynamically, but maychange the used uplink semi-statically. In order to change the uplinkused, the terminal performs a random access (i.e., preambletransmission) at a new uplink frequency to be used.

FIG. 1D is a diagram for describing a process in which a standby modeterminal selects one uplink frequency according to an embodiment of thedisclosure.

Referring to FIG. 1D, a base station 1 d-10 transmits informationrequired for selecting one of a plurality of uplinks and random accessconfiguration information applied in each uplink to a terminal 1 d-05using the system information (1 d-15). The random access configurationinformation includes radio resource information for the random access,information for calculating preamble transmission power, and preamblegroup information to be used for transmission.

The terminal receiving the information selects one of the uplinkfrequencies using the information (1 d-20). In this case, the terminalconsiders even whether the selected frequency is supportable togetherand when the selected frequency is not supportable, the terminal selectsanother possible frequency (1 d-25).

The terminal needs to select the uplink frequency that may provide theuplink service area. Therefore, the base station needs to providerequired information so that the terminal may determine which uplinkfrequency may provide an appropriate service area. The method forconfiguring the above information is various. The disclosure proposesseveral methods.

First Method:

The base station provides a P_EMAX value corresponding to each uplinkfrequency as the system information. The P_EMAX is defined as below.

Maximum TX power level a UE may use when transmitting on the uplink inthe cell (dBm)

The terminal receiving the value selects the uplink frequency providingthe smallest value (P_EMAX−P_PowerClass) or selects one of the uplinkfrequencies with the value of (P_EMAX−P_PowerClass) not exceeding 0according to a predetermined rule. The predetermined rule is proposedbelow again. The value of P_PowerClass is defined as follows.

Maximum radio frequency (RF) output power of the UE (dBm) according tothe UE power class

Second Method:

The base station provides one signal strength value corresponding toeach uplink frequency as the system information. The terminal receivingthe value selects one of the uplink frequencies providing the signalstrength value smaller than the P_PowerClass value thereof according toa predetermined rule.

There may be a plurality of uplink frequencies that may provide anappropriate uplink frequency domain. That is, in FIG. 1B, the pluralityof uplink frequencies provides an appropriate service area to the secondterminal 1 b-45. Therefore, in this case, whether the service area maybe provided is not important. When there are the plurality of uplinkfrequencies that may provide the appropriate uplink frequency domain, amethod for the terminal to decide one uplink frequency is as follows.

First Method:

There may be uplink frequencies that may provide the appropriate uplinkfrequency domain, but a predetermined uplink frequency is selected. Forexample, in FIG. 1C, the next-generation mobile communication frequencyis selected of the next generation mobile communication frequency 1 c-05of 3.5 GHz and the supplementary uplink frequency 1 c-10 of 1.8 GHz.

Second Method:

One of the uplink frequencies that may provide the appropriate uplinkfrequency domain is randomly selected.

Third Method:

The base station provides one value between 0 and 1 as the systeminformation. The terminal generates one random value between 0 and 1 andthen selects one uplink frequency according to a value larger or smallerthan the value provided from the base station.

Fourth Method:

The base station provides 10 bits of bitmap information corresponding toaccess classes (AC) 0 to 9 as the system information. In this case, aterminal corresponding to AC marked as 0 selects the next-generationmobile communication frequency and a terminal corresponding to AC markedas 1 selects the supplementary uplink frequency. The opposite is alsovalid.

Fifth Method:

The base station provides information indicating a congestion for eachof the next-generation mobile communication frequency and thesupplementary uplink frequency as the system information. Based on theinformation, the terminal selects one frequency with a low congestion.

Sixth Method:

The base station provides information indicating barring configurationinformation for each of the next-generation mobile communicationfrequency and the supplementary uplink frequency as the systeminformation. Based on the barring configuration information, theterminal selects a frequency with a high access probability.

The terminal transmits the preamble when an access is required at theuplink frequency determined based on the above methods (1 d-30).

FIG. 1E is a flowchart of an operation of selecting one uplink frequencyby the standby mode terminal according to an embodiment of thedisclosure.

Referring to FIG. 1E, in operation 1 e-05, the terminal receives thesystem information from the base station. The system informationincludes information required for selecting one of a plurality ofuplinks and random access configuration information applied in eachuplink.

In operation 1 e-10, the terminal selects one uplink frequency accordingto the provided information and a predetermined rule.

In operation 1 e-15, the terminal determines whether the selectedfrequency is supportable to decide an uplink frequency to be finallyused.

In operation 1 e-20, the terminal transmits the preamble when the accessis required using the selected uplink frequency.

FIG. 1F is a diagram for describing a process in which a connection modeterminal selects one uplink frequency according to an embodiment of thedisclosure.

Referring to FIG. 1F, the uplink frequency decided in a standby mode isalso used even in a connection mode. However, when the base station orthe terminal makes a request during the connection mode, the case may bechanged. A terminal 1 f-05 transmits terminal capability information toa base station 1 f-10 (1 f-15). The capability information includesuplink frequency information that the terminal may support. Based on afeedback state in an uplink frequency which is currently used togetherwith the information, the base station decides the uplink frequency tobe changed (1 f-17). The base station triggers the random access to theterminal using a physical downlink control channel (PDCCH) order. Inthis case, the PDCCH order includes uplink frequency information forperforming the random access. This means changing to the uplinkfrequency. The uplink frequency information may be provided to theterminal using radio resource control (RRC) signaling or a medium accesscontrol (MAC) CE (1 f-20). The terminal performs the random access tothe indicated uplink frequency (1 f-25). Thereafter, the frequency isused in uplink data transmission.

FIG. 1G is a diagram for describing a process of configuring one uplinkfrequency to a terminal that switches a connection mode to a standbymode or an INACTIVE mode according to an embodiment of the disclosure.

Referring to FIG. 1G, when the terminal is switched from the connectionmode to the standby mode or the INACTIVE mode, the base station maydedicatedly indicate uplink frequency information which the terminal isto apply in the standby mode. A terminal 1 g-05 transmits the terminalcapability information to a base station 1 g-10 (1 g-15). The capabilityinformation includes uplink frequency information that the terminal maysupport. When the base station transmits a Release message for switchingthe terminal to the standby mode or the INACTIVE mode, the base stationinserts the uplink frequency information to be applied in the standbymode or the INACTIVE mode in the message (1 g-20). The terminalreceiving the frequency information transmits the preamble at theindicated uplink frequency when the random access is required (1 g-25).

The uplink frequency information indicated in the Release message isvalid only until a specific condition is satisfied. For example, theRelease message includes a specific timer value. The timer operatesimmediately after receiving the Release message or when the terminalreceiving the message is switched to the standby mode or the INACTIVEmode. When the timer expires, the indicated uplink frequency informationis no longer valid. Another method is that the indicated uplinkfrequency is no longer valid when the terminal is out of the servicearea of a cell providing the Release message. Alternatively, bothmethods may be applied at the same time.

Upon selecting the supplementary uplink frequency, the terminaltransmits the preamble and msg3 at the frequency and receives RAR andmsg4 from PCell.

FIG. 1H illustrates the structure of the terminal according to anembodiment of the disclosure.

Referring to FIG. 1H, the terminal includes a RF processor 1 h-10, abaseband processor 1 h-20, a storage 1 h-30, and a controller 1 h-40.

The RF processor 1 h-10 performs a function of transmitting andreceiving a signal through a radio channel such as band conversion andamplification of the signal. That is, the RF processor 1 h-10up-converts a baseband signal provided from the baseband processor 1h-20 to an RF band signal and then transmits the RF band signal throughan antenna and down-converts the RF band signal received through theantenna to the baseband signal. For example, the RF processor 1 h-10 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a digital to analog converter (DAC), an analog todigital converter (ADC), and the like. In the figure, only one antennais illustrated, but the terminal may have multiple antennas. Inaddition, the RF processor 1 h-10 may include multiple RF chains.Furthermore, the RF processor 1 h-10 may perform beamforming. For thebeamforming, the RF processor 1 h-10 may adjust phases and sizes ofsignals transmitted and received through the multiple antennas orantenna elements. Further, the RF processor may perform multiple inputmultiple output (MIMO) and may receive multiple layers when performing aMIMO operation.

The baseband processor 1 h-20 performs a conversion function between thebaseband signal and a bitstream according to a physical layerspecification of the system. For example, at the time of datatransmission, the baseband processor 1 h-20 generates complex symbols byencoding and modulating transmission bitstreams. In addition, uponreceiving data, the baseband processor 1 h-20 demodulates and decodesthe baseband signal provided from the RF processor 1 h-10 to restore thereceived bitstream. For example, when the data is transmitted accordingto an OFDM scheme, the baseband processor 1 h-20 generates the complexsymbols by encoding and modulating the transmission bit streams and mapsthe complex symbols to subcarriers and then configures OFDM symbolsthrough an inverse fast Fourier transform (IFFT) operation and cyclicprefix (CP) insertion. In addition, upon receiving data, the basebandprocessor 1 h-20 divides the baseband signal provided from the RFprocessor 1 h-10 into OFDM symbol units and restores the signals mappedto the subcarriers through a fast Fourier transform (FFT) operation andthen restores the received bitstreams through demodulation and decoding.

The baseband processor 1 h-20 and the RF processor 1 h-10 transmit andreceive signals as described above. As a result, the baseband processor1 h-20 and the RF processor 1 h-10 may be referred to as a transmitter,a receiver, a transceiver, or a communication unit. Further, at leastone of the baseband processor 1 h-20 and the RF processor 1 h-10 mayinclude multiple communication modules in order to support multipledifferent radio access technologies. In addition, at least one of thebaseband processor 1 h-20 and the RF processor 1 h-10 may includedifferent communication modules in order to process signals of differentfrequency bands. For example, the different radio access technologiesmay include a wireless local area network (LAN) (e.g., IEEE 802.11), acellular network (e.g., LTE), and the like. In addition, the differentfrequency bands may include a super high frequency (SHF) band (e.g.,2.NRHz, NRhz) and a millimeter wave (e.g., 60 GHz) band.

The storage 1 h-30 stores data such as a basic program, an applicationprogram, and configuration information for the operation of theterminal. In particular, the storage 1 h-30 may store informationrelated to a second access node performing wireless communication usinga second radio access technology. In addition, the storage 1 h-30provides the stored data according to a request of the controller 1h-40.

The controller 1 h-40 controls overall operations of the terminal. Forexample, the controller 1 h-40 transmits and receives the signalsthrough the baseband processor 1 h-20 and the RF processor 1 h-10. Inaddition, the controller 1 h-40 writes and reads the data to and fromthe storage 1 h-30. To this end, the controller 1 h-40 may include atleast one processor. For example, the controller 1 h-40 may include acommunication processor (CP) for performing a control for communicationand an application processor (AP) for controlling a higher layer such asan application program. Further, the controller 1 h-40 may include amultiple connection processor 1 h-42 that performs processing foroperating in a multiple connection mode.

FIG. 1I illustrates a block configuration of a main base station inwireless communication system according to an embodiment of thedisclosure.

Referring to FIG. 1I, the base station is configured to include an RFprocessor 1 i-10, a baseband processor 1 i-20, a backhaul communicationunit 1 i-30, a storage 1 i-40, and a controller 1 i-50.

The RF processor 1 i-10 performs a function of transmitting andreceiving the signal through the radio channel such as the bandconversion and amplification of the signal. That is, the RF processor 1h-10 up-converts the baseband signal provided from the basebandprocessor 1 h-20 to the RF band signal and then transmits the RF bandsignal through the antenna and down-converts the RF band signal receivedthrough the antenna to the baseband signal. For example, the RFprocessor 1 i-10 may include the transmission filter, the receptionfilter, the amplifier, the mixer, the oscillator, the DAC, the ADC, andthe like. In the figure, only one antenna is illustrated, but the firstaccess node may include multiple antennas. In addition, the RF processor1 i-10 may include multiple RF chains. Furthermore, the RF processor 1i-10 may perform the beamforming. For the beamforming, the RF processor1 i-10 may adjust the phases and sizes of the respective signalstransmitted and received through the multiple antennas or antennaelements. The RF processor may perform a downlink MIMO operation bytransmitting one or more layers.

The baseband processor 1 i-20 performs the conversion function betweenthe baseband signal and the bitstream according to the physical layerspecification of the system. For example, at the time of datatransmission, the baseband processor 1 i-20 generates the complexsymbols by encoding and modulating the transmission bitstreams. Inaddition, upon receiving data, the baseband processor 1 i-20 demodulatesand decodes the baseband signal provided from the RF processor 1 i-10 torestore the received bitstream. For example, when the data istransmitted according to the OFDM scheme, the baseband processor 1 i-20generates the complex symbols by encoding and modulating thetransmission bitstreams and maps the complex symbols to the subcarriersand then configures the OFDM symbols through the IFFT operation and theCP insertion. In addition, upon receiving data, the baseband processor 1i-20 divides the baseband signal provided from the RF processor 1 i-10into the OFDM symbol units and restores the signals mapped to thesubcarriers through the FFT operation and then restores the receivedbitstreams through the demodulation and decoding. The baseband processor1 i-20 and the RF processor 1 i-10 transmit and receive the signals asdescribed above. As a result, the baseband processor 1 i-20 and the RFprocessor 1 i-10 may be referred to as the transmitter, the receiver,the transceiver, the communication unit, or a wireless communicationunit.

The backhaul communication unit 1 i-30 provides an interface forperforming communication with other nodes in a network. That is, thebackhaul communication unit 1 i-30 converts bitstreams transmitted fromthe main base station to other nodes, for example, a sub-base station, aCN, etc., into a physical signal and converts the physical signalreceived from the other node into the bitstream.

The storage 1 i-40 stores the data such as the basic program, theapplication program, and the configuration information for the operationof the terminal. In particular, the storage 1 i-40 may store informationon a bearer allocated to the connected terminal, a measurement resultsreported from the connected terminal, and the like. In addition, thestorage 1 i-40 may store information serving as a criterion fordetermining whether to provide multiple connections to the terminal orwhether to suspend the multiple connections. Further, the storage 1 i-40provides the stored data according to the request of the controller 1i-50.

The controller 1 i-50 controls the overall operations of the main basestation. For example, the controller 1 i-50 transmits and receives thesignals through the baseband processor 1 i-20 and the RF processor 1i-10 or the backhaul communication unit 1 i-30. In addition, thecontroller 1 i-50 writes and reads the data to and from the storage 1i-40. To this end, the controller 1 i-50 may include at least oneprocessor. Further, the controller 1 i-50 may include a multipleconnection processor 1 i-52 that performs processing for operating in amultiple connection mode.

Second Embodiment

Hereinafter, an operation principle of the disclosure will be describedin detail with reference to the accompanying drawings. Hereinbelow, indescribing the disclosure, detailed description of associated knownfunction or constitutions will be omitted if it is determined that theyunnecessarily make the gist of the disclosure unclear. In addition,terms to be described below as terms which are defined in considerationof functions in the disclosure may vary depending on the intention orusual practice of a user or an operator. Accordingly, the terms need tobe defined based on contents throughout this specification.

A term used for identifying a connection node used in the followingdescription, a term referring to network entities, a term referring tomessages, a term indicating an interface between network objects, a termindicating various identification information, etc. are illustrated forconvenience of description. Therefore, the disclosure is not limited toterms to be described later, and other terms referring to objects havingequivalent technical meanings can be used.

Hereinafter, for convenience of description, in the disclosure, used areterms and names defined in the 3rd generation partnership project longterm evolution (3GPP LTE) standard which is the latest standard amongexisting communication standards. However, the disclosure is not limitedby the above-mentioned terms and names, and can be equally applied tosystems conforming to other standards. In particular, the disclosure isapplicable to 3GPP new ratio (NR: 5th generation mobile communicationstandard).

FIG. 2A is a diagram illustrating a structure of an LTE system accordingto an embodiment of the disclosure.

Referring to FIG. 2A above, the wireless communication system includesmultiple base stations 2 a-05, 2 a-10, 2 a-15, and 2 a-20, an MME 2a-25, and a serving-gateway (S-GW) 2 a-30. A UE or terminal 2 a-35 isconnected to an external network through the base stations 2 a-05, 2a-10, 2 a-15, and 2 a-20, and the S-GW 2 a-30.

The base stations 2 a-05, 2 a-10, 2 a-15, and 2 a-20 provide the radioaccess to terminals connected to the network as access nodes of acellular network. That is, in order to serve traffic of users, the basestations 2 a-05, 2 a-10, 2 a-15, and 2 a-20 collect and schedule thestate information such as the buffer state, the available transmissionpower state, and the channel state to support the connection between theterminals and a CN. The MME 2 a-25 as a device for performing variouscontrol functions as well as the mobility management function for theterminal, and is connected to multiple base stations and the S-GW 2 a-30provides a data bearer. Further, the MME 2 a-25 and the S-GW 2 a-30 mayfurther perform authentication and bearer management for the terminalconnected to the network and process packets which are reached from thebase stations 2 a-05, 2 a-10, 2 a-15, and 2 a-20 or packets to betransmitted to the base stations 2 a-05, 2 a-10, 2 a-15, and 2 a-20.

FIG. 2B is a diagram illustrating a radio protocol structure of the LTEsystem according to an embodiment of the disclosure. The NR to bedefined in the future may be partially different from a radio protocolstructure in this figure, but will be described for convenience ofdescription of the disclosure.

Referring to FIG. 2B, the radio protocol of the LTE system includespacket data convergence protocols (PDCPs) 2 b-05 and 2 b-40, radio linkcontrols (RLCs) 2 b-10 and 2 b-35, and MACs 2 b-15 and 2 b-30 in each ofthe terminal and eNB. The PDCPs 2 b-05 and 2 b-40 are responsible foroperations such as IP header compression/decompression and the RLCs 2b-10 and 2 b-35 reconfigures the PDCP packet data unit (PDU) reconfigurePDCP PDU to an appropriate size. The MACs 2 b-15 and 2 b-30 areconnected to multiple RLC layer devices configured in one terminal andperform operations of multiplexing the RLC PDUs to the MAC PDUs anddemultiplexing the RLC PDUs from the MAC PDUs. The physical layer 2 b-20and 2 b-25 channel-code and modulate the higher layer data and convertthe higher layer data into the OFDM symbol and transmit the OFDM symbolthrough the radio channel or demodulate and channel-decode the OFDMsymbol received through the radio channel and transmit the OFDM symbolto the higher layer. Further, even in the physical layer, for additionalerror correction, hybrid ARQ (HARQ) is used and a receiving sidetransmits whether to receive a packet transmitted by a transmitting sideas 1 bit. This is referred to as HARQ acknowledgement (ACK)/negativeacknowledgement (NACK) information. Downlink HARQ ACK/NACK informationfor uplink transmission may be transmitted through a physical hybrid-ARQindicator channel (PHICH) physical channel and uplink HARQ ACK/NACKinformation for downlink transmission may be transmitted through aphysical uplink control channel (PUCCH) or a physical uplink sharedchannel (PUSCH) physical channel. The PUSCH is used for the terminal totransmit to the base station downlink channel status information (CSI),a scheduling request (SR), and the like as well as the HARQ ACK/NACKinformation. The SR is 1-bit information and when the terminal transmitsthe SR to a resource in a PUCCH configured by the base station, the basestation recognizes that the corresponding terminal has data to betransmitted in the uplink and allocates an uplink resource. The terminalmay transmit a detailed buffer status report (BSR) message as the uplinkresource. The base station may allocate a plurality of SR resources toone terminal.

Meanwhile, the physical (PHY) layer may be constituted by one or aplurality of frequencies/carriers and technology of simultaneouslyconfiguring and using the plurality of frequencies in one base stationis referred to as carrier aggregation (CA). The CA technology is atechnique in which unlike a case where only one carrier is used forcommunication between the terminal (UE) and the base station (E-UTRANNodeB (eNB)), a transmission amount may be dramatically increased asmany as secondary carriers by additionally using a primary carrier andone or a plurality of secondary carriers. Meanwhile, In LTE, a cell inthe base station using the primary carrier is called primary cell(PCell) and a secondary carrier is called secondary cell (SCell).Technology in which the CA function is extended to two base stations isreferred to as dual connectivity (DC). In the DC technology, theterminal concurrently connects a master base station (Master E-UTRANNodeB (MeNB)) and a secondary base station (secondary E-UTRAN NodeB(SeNB) (MCG)) and cells belonging to the MeNB are referred to as amaster cell group (MCG) and cells belonging to the SeNB are referred toas a secondary cell group (SCG). There is a representative cell for eachcell group and a representative cell of the MCG is referred to as aPCell and a representative cell of the SCG is referred to as a primarysecondary cell (PSCell). When using the aforementioned NR, the MCG isused as the LTE technology and the SCG is used as the NR, and as aresult, the terminal may use both the LTE and the NR.

Although not illustrated in the figure, an RRC layer exist in a higherlayer of the PDCP layer of each of the terminal and the base station andthe RRC layer may transmit and receive connection and measurementrelated control messages for RRC. For example, a measurement may beinstructed to the terminal using an RRC layer message and the terminalmay report a measurement result to the base station using the RRC layermessage.

Meanwhile, the transmission units of the PCell and the SCell may be thesame or different. For example, in the LTE, the transmission units ofthe PCell and the SCell may be the same in 1 ms unit, but in the NR, thetransmission unit (slot) in the PCell is 1 ms, but the transmission unitin the SCell may have a length of 0.5 ms.

Table 1 below shows information on the length of the slot available ineach serving cell (i.e., PCell or SCell) according to numerology (oraccording to a subcarrier interval) used by each serving cell in the NR.

TABLE 1 Secondary 15 30 60 120 240 carrier interval (kHz) Transmission 10.5 0.25 0.125 0.00625 unit (slot) length (ms) Number of 1 2 4 8 12slots in subframe (1 ms)

Further, in the LTE and the NR, the following units are used in a framestructure in a radio interval (i.e., between the base station and theterminal).

-   -   Radio frame: Having a length of 1 ms and identified by system        frame number (SFN) every radio frame    -   Subframe: Having the length of 1 ms and having 10 subframes in        the radio frame. Identified by subframe numbers 0 to 9 in every        radio frame    -   Slot: Having a length depending on a set value as shown in the        table and a transmission unit when the base station and the        terminal transmit data.

FIG. 2C is a diagram for describing a discontinuous reception DRXoperation of the terminal according to an embodiment of the disclosure.

Referring to FIG. 2C, DRX is a technique that monitors only some PDCCHsaccording to the configuration information instead of monitoring allphysical downlink control channels (PDCCH) in order to obtain schedulinginformation according to the configuration of the base station forminimizing the power consumption of the terminal. A basic DRX operationhas a DRX period (2 c-00) and monitors the PDCCH only for onDuration (2c-05) time. In the connection mode, the DRX period has two values, longDRX and short DRX. In general, a long DRX period is applied and ifnecessary, the base station may additionally set the short DRX period.When both the long DRX period and the short DRX period are set, theterminal starts a short DRX timer and first repeats the short DRX cycleand when there is no new traffic until the short DRX timer expires, theterminal changes the short DRX period to the long DRX period. When thescheduling information for a new packet is received by the PDCCH duringthe on-duration (2 c-05) time (2 c-10), the terminal starts a DRXinactivity timer 2 c-15. The terminal maintains an active state duringthe DRX inactivity timer. That is, PDCCH monitoring is continued.Further, an HARQ RTT timer 2 c-20 also starts. The HARQ RTT timer isapplied to prevent the terminal from unnecessarily monitoring the PDCCHduring HARQ round trip time (RTT) and the terminal does not need toperform the PDCCH monitoring during a timer operation time. However,while the DRX inactivity timer and the HARQ RTT timer operatesimultaneously, the terminal continues to monitor the PDCCH based on theDRX inactivity timer. When the HARQ RTT timer expires, the DRXretransmission timer 2 c-25 starts. While the DRX retransmission timeroperates, the terminal needs to perform the PDCCH monitoring. Ingeneral, during the DRX retransmission timer operation, schedulinginformation for HARQ retransmission is received (2 c-30). Upon receivingthe scheduling information, the terminal immediately stops the DRXretransmission timer and starts the HARQ RTT timer again. Such anoperation is continued until the packet is successfully received (2c-35).

FIG. 2D is a diagram illustrating an embodiment in which a timing ofperforming a DRX operation is schematized in the situation where theplurality of transmission units coexists according to an embodiment ofthe disclosure.

Referring to FIG. 2D, it is assumed that the terminal is in theconnection mode (RRC_CONNECTED) state in which the terminal is connectedto the base station and SCell 2 d-03 is additionally configured from thebase station. The terminal in the connection mode state may transmit andreceive data to and from the base station.

When the base station configures SCell to the terminal, the base stationconfigures the transmission unit of the corresponding SCell. Thetransmission unit is generally referred to as a slot in the disclosure.In the example diagram, it is assumed that the slot length of the PCell(2 d-01) has a length of 1 ms as in the case of the subframe (2 d-51)and the slot length of the SCell has a length of ¼ (0.25 ms) (2 d-53).

Meanwhile, the base station may configure the DRX to reduce the powerconsumption of the terminal. The timer used for the DRX includes thefollowing timers as described above and the time unit for each timer isas follows. According to the present invention, onDuration timer (2d-11) is operated based on subframe unit (2 d-05) and HARQ RTT timer (2d-33, 2 d-37) and rtx timer (2 d-35) are operated based on slot unit (2d-07).

-   -   onDuration timer: Set to the number of slots in the reference        cell    -   short DRX cycle: set to the number of slots in the reference        cell (or set to the number of subframes)    -   short DRX cycle timer (2 d-23): set to the number of slots in        the reference cell    -   long DRX cycle: set to the number of slots in the reference cell        (or set to the number of subframes)    -   DRX inactivity timer: set to the number of slots in the        reference cell    -   HARQ RTT timer: set to the number of slots in the corresponding        cell in which transmission/retransmission is performed    -   DRX retransmission timer: set to the number of slots in the        corresponding cell in which transmission/retransmission is        performed

The slot of the reference cell may be the slot of the PCell or the slotof a cell having the longest transmission unit among all serving cells(i.e., PCell and SCell).

The terminal that receives the configuration repeats the correspondingcycle according to the configured cycle 2 d-21 and monitors the PDCCHduring onDuration (2 d-11), (2 d-13), (2 d-15), and (2 d-17). When thebase station transmits data to the terminal during the onDuration (2d-41), the terminal drives the HARQ RTT timer and the time unit at thistime is based on the number of slots 2 d-53 of the serving cell 2 d-03subjected to scheduling. In the example diagram, the time unit of theHARQ RTT timer is assumed as 3 serving cell slots (2 d-33). Since thedata is received during the onDuration, the terminal drives the DRXinactivity timer (2 d-31) to determine whether additional new data iscoming Meanwhile, when the HARQ RTT timer expires, the terminal drives aDRX retransmission timer and the terminal monitors the PDCCH while theDRX retransmission timer is driven (2 d-35). When the terminal receivesthe scheduling for retransmission on the PDCCH (2 d-43), the terminalstops the DRX retransmission timer that was being driven and then drivesthe HARQ RTT timer (2 d-37). Thereafter, when the terminal determinesthat the HARQ retransmission has been successfully completed before theHARQ RTT timer expires, the terminal does not operate the DRXretransmission timer any more. As illustrated, the HARQ RTT timer andthe DRX retransmission timer associated with the HARQ retransmission aredriven according a set length in the slot unit of the corresponding cellin which transmission and retransmission are performed, therebyperforming retransmission according to each transmission unit.

When an active time 2 d-61 and an inactive time 2 d-63 at which theterminal substantially monitors the PDCCH and transmits and receives thedata according to the driving of all timers are schematicallyillustrated, a pattern of 2 d-09 is shown.

FIG. 2E is a diagram illustrating an operational order of a terminal atthe time of performing the DRX operation in the situation where theplurality of transmission units coexists according to an embodiment ofthe disclosure.

Referring to FIG. 2E, it is assumed that the terminal is in theconnection mode (RRC_CONNECTED) state in which the terminal is connectedto the base station (2 e-01). Thereafter, the terminal receives the DRXconfiguration from the base station (2 e-03). The DRX configurationincludes timers required for DRX driving and the respective timers andthe time units of the respective timers are as follows.

-   -   onDuration timer: set to the number of slots in the reference        cell    -   short DRX cycle: set to the number of slots in the reference        cell (or set to the number of subframes)    -   short DRX cycle timer: set to the number of slots in the        reference cell    -   long DRX cycle: set to the number of slots in the reference cell        (or set to the number of subframes)    -   DRX inactivity timer: set to the number of slots in the        reference cell    -   HARQ RTT timer: set to the number of slots in the corresponding        cell in which transmission/retransmission is performed    -   DRX retransmission timer: set to the number of slots in the        corresponding cell in which transmission/retransmission is        performed

The slot of the reference cell may be the slot of the PCell or the slotof a cell having the longest transmission unit among all serving cells(i.e., PCell and SCell).

Accordingly, the terminal repeats the cycle according to the configuredcycle and monitors the PDCCH during onDuration. When there is new datatransmission in onDuration, the DRX inactivity timer is driven at theend of onDuration and the HARQ RTT timer is driven at the time ofreceiving the new data transmission. When the terminal receives the newdata transmission in the active time interval, the terminal performs theabove operation. In addition, when the HARQ RTT timer does notsuccessfully receive the packet until the expiration of the HARQ RTTtimer, the terminal drives the DRX retransmission timer and monitors thePDCCH for retransmission from the base station. Thereafter, when theterminal determines that the HARQ retransmission is successfullycompleted before the HARQ RTT timer expires, the terminal does not drivethe DRX retransmission timer any more. When both the long DRX period andthe short DRX period are set as described above, the terminal starts theshort DRX timer and first repeats the short DRX period and when there isno new traffic until the short DRX timer expires, the terminal changesthe short DRX period to the long DRX period. Thereafter, when newtraffic occurs, the terminal uses the short DRX period and repeats theabove procedure (2 e-05).

FIG. 2F is a block diagram of a terminal according to an embodiment ofthe disclosure.

Referring to FIG. 2F above, the terminal includes a RF processor 2 f-10,a baseband processor 2 f-20, a storage 2 f-30, and a controller 2 f-40.

The RF processor 2 f-10 performs a function of transmitting andreceiving a signal through a radio channel such as band conversion andamplification of the signal. That is, the RF processor 2 f-10up-converts the baseband signal provided from the baseband processor 2f-20 to the RF band signal and then transmits the RF band signal throughthe antenna and down-converts the RF band signal received through theantenna to the baseband signal. For example, the RF processor 2 f-10 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a DAC, an ADC, and the like. In FIG. 2F above,only one antenna is illustrated, but the terminal may have multipleantennas. In addition, the RF processor 2 f-10 may include multiple RFchains. Furthermore, the RF processor 2 f-10 may perform beamforming.For the beamforming, the RF processor 2 f-10 may adjust phases and sizesof signals transmitted and received through the multiple antennas orantenna elements.

The baseband processor 2 f-20 performs a conversion function between thebaseband signal and a bit string according to a physical layerspecification of the system. For example, at the time of datatransmission, the baseband processor 2 f-20 generates the complexsymbols by encoding and modulating the transmission bitstreams. Inaddition, upon receiving data, the baseband processor 2 f-20 demodulatesand decodes the baseband signal provided from the RF processor 2 f-10 torestore the received bitstream. For example, when the data istransmitted according to an OFDM scheme, the baseband processor 2 f-20generates the complex symbols by encoding and modulating thetransmission bit streams and maps the complex symbols to subcarriers andthen configures OFDM symbols through an IFFT operation and CP insertion.In addition, upon receiving data, the baseband processor 2 f-20 dividesthe baseband signal provided from the RF processor 2 f-10 into OFDMsymbol units and restores the signals mapped to the subcarriers througha FFT operation and then restores the received bitstreams throughdemodulation and decoding.

The baseband processor 2 f-20 performs a function of converting abaseband signal and a bit string according to a physical layerspecification of the system. For example, at the time of datatransmission, the baseband processor 2 f-20 generates complex symbols byencoding and modulating transmission bit streams. Also, upon receivingdata, the baseband processor 2 f-20 demodulates and decodes the basebandsignal provided from the RF processor 2 f-10 to recover the receivedbitstream. For example, in accordance with an OFDM scheme, the basebandprocessor 2 f-20 generates complex symbols by encoding and modulatingtransmission bit streams, transmits the complex symbols to subcarriers,and then constructs OFDM symbols through IFFT operation and CPinsertion. When receiving the data, the baseband processor 2 f-20divides the baseband signal provided from the RF processor 2 f-10 intoOFDM symbol units, performs FFT operation on subcarriers, restores themapped signals, and restores the received bit stream throughdemodulation and decoding.

The baseband processor 2 f-20 and the RF processor 2 f-10 transmit andreceive the signals as described above. As a result, the basebandprocessor 2 f-20 and the RF processor 2 f-10 may be referred to as atransmitter, a receiver, a transceiver, or a communication unit. Inaddition, at least one of the baseband processor 2 f-20 and the RFprocessor 2 f-10 may include different communication modules in order toprocess signals of different frequency bands. In addition, the differentfrequency bands may include a super high frequency (SHF) band (e.g., 2.5GHz and 5 GHz) and a millimeter wave (e.g., 60 GHz) band.

The storage 2 f-30 stores data such as a basic program, an applicationprogram, and configuration information for the operation of theterminal.

The controller 2 f-40 controls overall operations of the terminal. Forexample, the controller 2 f-40 transmits and receives the signalsthrough the baseband processor 2 f-20 and the RF processor 2 f-10. Inaddition, the controller 2 f-40 writes and reads the data to and fromthe storage 2 f-30. To this end, the controller 2 f-40 may include atleast one processor. For example, the controller 2 f-40 may include a CPfor performing a control for communication and an AP for controlling ahigher layer such as an application program. According to an embodimentof the disclosure, the controller 2 f-40 includes a multiple connectionprocessor 2 f-42 for performing a process for operating in a multipleconnection mode. For example, the controller 2 f-40 may control theterminal to perform the procedure shown in the operation of the terminalillustrated in FIG. 2F above.

According to an embodiment of the disclosure, the terminal determines aslot for monitoring the PDCCH according to the DRX configurationinformation configured from the base station and receives, transmits,and retransmits the PDCCH to reduce the power consumption of theterminal while reducing a delay.

Methods according to the claims or the embodiments described in theclaims or the specification of the disclosure may be implemented inhardware, software, or a combination of hardware and software.

When implemented in software, a computer-readable storage medium storingone or more programs (software modules) may be provided. One or moreprograms stored on a computer-readable storage medium are configured forexecution by one or more processors in an electronic device (configuredfor execution). The one or more programs include instructions that causethe electronic device to perform the methods according to theembodiments disclosed in the claims or the specification of thedisclosure.

Such programs (software modules and software) may be stored in a memorysuch as a random access memory, a non-volatile memory including a flashmemory, a read only memory (ROM), an electrically erasable programmableROM (EEPROM), a magnetic disc storage device, a compact disc-ROM(CD-ROM), a digital versatile disc (DVD) or other types of opticalstorage devices, or a magnetic cassette. Alternatively, the programs maybe stored in a memory configured by combinations of some or all of them.Further, multiple configuration memories may be included.

In addition, the program may be stored in attachable storage deviceswhich may be accessed through a communication network such as acommunication network such as the Internet, an Intranet, a LAN, a wideLAN (WLAN, or a storage area network (SAN) and a communication networkconfigured by a combination thereof. Such a storage device may beconnected to an apparatus that performs an embodiment of the disclosurevia an external port. Further, a separate storage device on thecommunication network may be connected to an apparatus that performs anembodiment of the disclosure.

In the specific embodiments of the disclosure described above, theelements included in the disclosure are expressed singular or plural inaccordance with the specific embodiment shown. However, it is to beunderstood that the singular or plural representations are selectedappropriately for the sake of convenience of description, and thedisclosure is not limited to the singular or plural constituentelements, and even elements by the plural representations may beconstituted by a single element or even an element by the singularrepresentation may be constituted by plural elements.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made withoutdeparting from the spirit and scope of the disclosure as defined by theappended claims and their equivalents.

What is claimed is:
 1. A method performed by a terminal in a wirelesscommunication system, the method comprising: receiving, from a basestation (BS), random access configuration information; selecting one ofan uplink (UL) carrier or a supplementary uplink (SUL) carrier toperform a random access, based on the random access configurationinformation; transmitting, to the BS, a first random access preamble onthe selected one of the UL carrier and the SUL carrier; transmitting, tothe BS, capability information of the terminal indicating whether theterminal supports the other of the UL carrier and the SUL carrier forswitching; receiving, from the BS on a physical downlink control channel(PDCCH), information indicating the other of the UL carrier and the SULcarrier based on the capability information of the terminal; andtransmitting, to the BS, a second random access preamble on the other ofthe UL carrier and the SUL carrier, based on the information, whereinthe UL carrier and the SUL carrier are associated with one downlinkcarrier configured for the terminal.
 2. The method of claim 1, whereinthe random access configuration information includes first informationon a resource for a random access, second information on a threshold forselection a carrier and third information on a power control parameterfor transmitting the first random access preamble.
 3. The method ofclaim 2, wherein the selected one of the UL carrier and the SUL carrieris determined based on the second information.
 4. The method of claim 1,wherein the random access configuration information is included insystem information broadcasted by the BS.
 5. A method for performing arandom access by a base station (BS) in a wireless communication system,the method comprising: transmitting, to a terminal, random accessconfiguration information; receiving, from the terminal, a first randomaccess preamble on one of an uplink (UL) carrier and a supplementaryuplink (SUL) carrier, wherein the one of the UL carrier and the SULcarrier is selected by the terminal based on the random accessconfiguration information; receiving, from the terminal, data on theselected uplink carrier of the UL carrier and the SUL carrier;receiving, from the terminal, capability information of the terminalindicating whether the terminal supports the other of the UL carrier andthe SUL carrier for switching; transmitting, to the terminal on aphysical downlink control channel (PDCCH), information indicating theother of the UL carrier and the SUL carrier based on the capabilityinformation of the terminal; and receiving, from the terminal, a secondrandom access preamble on the other of the UL carrier and the SULcarrier, based on the information, wherein the UL carrier and the SULcarrier are associated with one downlink carrier configured for theterminal.
 6. The method of claim 5, wherein the random accessconfiguration information includes first information on a resource for arandom access, second information on a threshold for selection a carrierand third information on a power control parameter for transmitting thefirst random access preamble.
 7. The method of claim 6, wherein theselected one of the UL carrier and the SUL carrier is determined basedon the second information.
 8. The method of claim 5, wherein the randomaccess configuration information is included in system informationbroadcasted by the BS.
 9. A terminal in a wireless communication system,the terminal comprising: a transceiver; and at least one processorconfigured to: control the transceiver to receive, from a base station(BS), random access configuration information, select one of an uplink(UL) carrier or a supplementary uplink (SUL) carrier to perform a randomaccess, based on the random access configuration information, controlthe transceiver to transmit, to the BS, a first random access preambleon the selected one of the UL carrier and the SUL carrier, control thetransceiver to transmit, to the BS, capability information of theterminal indicating whether the terminal supports the other of the ULcarrier and the SUL carrier for switching, control the transceiver toreceive, from the BS on a physical downlink control channel (PDCCH),information indicating the other of the UL carrier and the SUL carrierbased on the capability information of the terminal, and control thetransceiver to transmit, to the BS, a second random access preamble onthe other of the UL carrier and the SUL carrier, based on theinformation, wherein the UL carrier and the SUL carrier are associatedwith one downlink carrier configured for the terminal.
 10. The terminalof claim 9, wherein the random access configuration information includesfirst information on a resource for a random access, second informationon a threshold for selection a carrier and third information on a powercontrol parameter for transmitting the first random access preamble. 11.The terminal of claim 10, wherein the selected one of the UL carrier andthe SUL carrier is determined based on the second information.
 12. Theterminal of claim 9, wherein the random access configuration informationis included in system information broadcasted by the BS.
 13. A basestation (BS) in a wireless communication system, the BS comprising: atransceiver; and at least one processor configured to: control thetransceiver to transmit, to a terminal, random access configurationinformation, control the transceiver to receive, from the terminal, afirst random access preamble on one of an uplink (UL) carrier and asupplementary uplink (SUL) carrier, wherein the one of the UL carrierand the SUL carrier is selected by the terminal based on the randomaccess configuration information, control the transceiver to receive,from the terminal, data on the selected uplink carrier of the UL carrierand the SUL carrier, control the transceiver to receive, from theterminal, capability information of the terminal indicating whether theterminal supports the other of the UL carrier and the SUL carrier forswitching, control the transceiver to transmit, to the terminal on aphysical downlink control channel (PDCCH), information indicating theother of the UL carrier and the SUL carrier based on the capabilityinformation of the terminal, and control the transceiver to receive,from the terminal, a second random access preamble on the other of theUL carrier and the SUL carrier, based on the information, wherein theone of the UL carrier and the SUL carrier is selected by the terminalbased on the random access configuration information, and wherein the ULcarrier and the SUL carrier are associated with one downlink carrierconfigured for the terminal.
 14. The BS of claim 13, wherein the randomaccess configuration information includes first information on aresource for a random access, second information on a threshold forselection a carrier and third information on a power control parameterfor transmitting the first random access preamble, and wherein theselected one of the UL carrier and the SUL carrier is determined basedon the second information.
 15. The BS of claim 14, wherein the randomaccess configuration information is included in system informationbroadcasted by the BS.